蟒蛇 - BeautifulSoup - 如何检查，如果结果集包含一个元素 [英] Python - BeautifulSoup - how to check if ResultSet contains an element

问题描述

我做一些网页刮，但我想出的东西，我想不通。基本上，我需要检查，如果我的ResultSet元素RELEASEDATE的第0元素包含内容作为

  [＆LT;元CONTENT =1992年9月11日itemprop =datePublished/＆GT;]
 

但是，当内容是不是在标签，我得到这样

错误

 回溯（最后最近一次调用）：
文件＆LT;＆标准输入GT;，1号线，上述＆lt;＆模块GT;
文件imdbQuestion.py18行，上述＆lt;＆模块GT;
如果RELEASEDATE [0] ['内容']：
文件建立/ bdist.macosx-10.8-英特尔/蛋/ BS4 / element.py，线路879，在__getitem__
KeyError异常：内容
 

我

如何检查'内容'是RELEASEDATE没有导致错误？

此外，我怎么能不管提取我想出来的ResultSet对象？

满code是：

 进口要求
从BS4进口BeautifulSoup文件= codecs.open（'imdb.txt'，'W'，编码=UTF-8）通过最后一个值#iterate
对于增量范围（7,10）：
    imdbNum ='015008'+ STR（增量）
    URL ='http://www.imdb.com/title/tt'+ imdbNum    网址code = requests.get（URL）
    汤= BeautifulSoup（URL code.content）    ＃获取的发布日期
    RELEASEDATE = soup.findAll（ATTRS = {'itemprop'：'datePublished'}）
    ABC = RELEASEDATE
        #ERROR检查 - 分配。到RELEASEDATE如果RELEASEDATE [0]是空白
        ＃如果不是空白，检查'内容'是RELEASEDATE [0]。如果是这样，我们是很好的。如果没有，分配'检查'，以RELEASEDATE [0]
    如果RELEASEDATE：
        如果RELEASEDATE [0] ['内容']：
            RELEASEDATE = RELEASEDATE [0] ['内容']
        其他：
            RELEASEDATE ='检查'
    其他：
        RELEASEDATE ='。    打印RELEASEDATE
    file.close（）
 

解决方案

针对的 Tag.attrs 字典：

 如果RELEASEDATE：
    如果RELEASEDATE内容[0] .attrs：
        RELEASEDATE = RELEASEDATE [0] ['内容']
    其他：
        RELEASEDATE ='检查'
 

或 dict.get（）方法上属性：

 如果RELEASEDATE：
    RELEASEDATE = RELEASEDATE [0] .attrs.get（'内容'，'检查'）
 

快速演示：

 ＆GT;＆GT;＆GT;进口要求
＆GT;＆GT;＆GT;从BS4进口BeautifulSoup
＆GT;＆GT;＆GT; imdbNum ='0150087'
＆GT;＆GT;＆GT; URL ='http://www.imdb.com/title/tt'+ imdbNum
＆GT;＆GT;＆GT;网址code = requests.get（URL）
＆GT;＆GT;＆GT;汤= BeautifulSoup（URL code.content）
＆GT;＆GT;＆GT; RELEASEDATE = soup.findAll（ATTRS = {'itemprop'：'datePublished'}）
＆GT;＆GT;＆GT; RELEASEDATE [0]
＆LT;元CONTENT =1966至1904年itemprop =datePublished/＆GT;
＆GT;＆GT;＆GT; RELEASEDATE [0] .attrs
{'内容'：'1966至1904年，itemprop'：'datePublished'}
＆GT;＆GT;＆GT;在RELEASEDATE [0] .attrs内容
真正
＆GT;＆GT;＆GT; RELEASEDATE [0] .attrs.get（'内容'，'检查'）
1966至1904年
 

I am doing some web-scraping, but I've come up with something that I can't figure out. Basically, I need to check if the 0'th element of my ResultSet element releaseDate contains 'content' as in

[<meta content="1992-09-11" itemprop="datePublished"/>]

But when 'content' is not in the tag, I get an error like

Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "imdbQuestion.py", line 18, in <module>
if releaseDate[0]['content']:
File "build/bdist.macosx-10.8-intel/egg/bs4/element.py", line 879, in __getitem__
KeyError: 'content'

How can I check if 'content' is in releaseDate without causing an error?

Additionally, how can I extract whatever I want out of ResultSet objects?

The full code is:

import requests
from bs4 import BeautifulSoup

file = codecs.open('imdb.txt', 'w', encoding = 'utf-8')

#iterate through last value
for increment in range(7,10):
    imdbNum = '015008' + str(increment)
    url = 'http://www.imdb.com/title/tt' + imdbNum

    urlCode = requests.get(url)
    soup = BeautifulSoup(urlCode.content)

    #get release date
    releaseDate = soup.findAll(attrs={'itemprop':'datePublished'})
    abc = releaseDate
        #error checking - assign '.' to releaseDate if releaseDate[0] is blank
        #if not blank, check if 'content' is in releaseDate[0]. if so, we are good.  if not, assign 'CHECK' to releaseDate[0]
    if releaseDate:
        if releaseDate[0]['content']:
            releaseDate = releaseDate[0]['content']
        else:
            releaseDate = 'CHECK'
    else:
        releaseDate = '.'

    print releaseDate
    file.close()

解决方案

Test against the Tag.attrs dictionary:

if releaseDate:
    if 'content' in releaseDate[0].attrs:
        releaseDate = releaseDate[0]['content']
    else:
        releaseDate = 'CHECK'

or use the dict.get() method on that attribute:

if releaseDate:
    releaseDate = releaseDate[0].attrs.get('content', 'CHECK')

Quick demo:

>>> import requests
>>> from bs4 import BeautifulSoup
>>> imdbNum = '0150087'
>>> url = 'http://www.imdb.com/title/tt' + imdbNum
>>> urlCode = requests.get(url)
>>> soup = BeautifulSoup(urlCode.content)
>>> releaseDate = soup.findAll(attrs={'itemprop':'datePublished'})
>>> releaseDate[0]
<meta content="1966-04" itemprop="datePublished"/>
>>> releaseDate[0].attrs
{'content': '1966-04', 'itemprop': 'datePublished'}
>>> 'content' in releaseDate[0].attrs
True
>>> releaseDate[0].attrs.get('content', 'CHECK')
'1966-04'

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